1. Field
Apparatuses consistent with exemplary embodiments relate to an illumination apparatus of a projection-type image display apparatus, and more particularly, to an illumination apparatus using laser diodes as a light source and a projection-type image display apparatus using the same.
2. Description of the Related Art
In general, light emitting diodes (LEDs) are widely used as light sources for illumination apparatus used in projection-type image display apparatuses, such as projectors. However, since rays coming from a light emitting diode are widely spread, there needs to be an optical device, such as one or more lenses, for collecting the dispersed rays, however, this is difficult.
Also, the larger the screen of a display is, the brighter the illumination apparatus must be. Thus, an illumination apparatus using light emitting diodes as a light source needs would need to increase the output of the light emitting diodes in order to increase brightness. This could require the development of new, higher output, light emitting diodes.
Alternately, as another way to increase the brightness of an illumination apparatus, laser diodes may be used, rather than light emitting diodes, as a light source. In this case, as a laser diode has better light linearity than a light emitting diode with the same power, an illumination apparatus using laser diodes can emit brighter light than an illumination apparatus using light emitting diodes.
However, in order to use laser diodes in an image display apparatus with a large screen, the output light amount of a laser diode light source needs to be increased. As one way to increase the light amount output by a laser diode light source, a power of the laser diode itself may be increased. However, while increasing the power of a laser diode increases the light amount, it also increases the heat that is generated, which means that the cooling of the light source must also be taken into consideration. When a cooling apparatus is used, there is the additional problem that the overall size of the illumination apparatus is increased, and, therefore, the structure thereof becomes more complicated.
As another way to increase the brightness of an illumination apparatus, the number of laser diodes used in the light source may be increased. However, increasing the number of laser diodes used also increases the heat that is generated, so there is still an issue of the need for a cooling apparatus. Accordingly, there is also an issue of an increased size of the illumination apparatus and more complicated structure thereof.
Therefore, without increasing the number of the laser diodes or increasing the power of the laser diodes themselves, there should be a way to increase the light amount of an illumination apparatus using laser diodes as a light source.